This application claims the priority of German application no. 196 25 556.2 and PCT/EP97/02754, filed Jun. 26, 1996 and May 28, 1997, respectively, the disclosures of which are expressly incorporated by reference herein.
The invention relates to a swivel brake for doors with a varying inclination of their swivelling axis with respect to the vertical, such as, for example, for car doors.
DE 44 06 824 C describes a hinge having a swivel catch which, by means of circular wedge profiles on the hinge pin and in the part bearing the hinge pin, inhibits swivelling of the door by friction and/or by elastic deformation of these bearing parts. The intention thereby is for the door to have self-locking in all swivelling positions of its opening angle range.
Motor-vehicle doors, in particular, are required not to shut by themselves, unintentionally, even when the motor vehicle is parked so as to tilt longitudinally or transversely. The magnitude of the moment which triggers this shutting, and the kinetic energy which a shutting door picks up, depends on the opening angle and the door mass. In addition, the moment magnitude and kinetic energy depend substantially on the position of the door swivelling axis in space, i.e. on the inclination of a motor vehicle parked such that it tilts. Provided that the doors are hinged at the front, the "shutting moment" decreases when a vehicle is parked uphill and has a decreasing opening angle, and increases when a vehicle is parked such that it tilts transversely (at the door situated uphill).
Since, in the case of a reverse movement of the door, such as when opening the door on the uphill side of a vehicle parked such that it tilts about the longitudinal axis, the braking torque applied by a swivel catch has to be overcome, this braking torque must also not be too great.
Accordingly, the invention is directed to specifying a dimensioning rule for the braking action of the swivel brake, by way of which rule these requirements, which in part contradict one another, can best be met. The invention achieves this objective by way of the general dimensioning rule which, rather than an arbitrary development of the braking torque of the swivel brake between an assumed initial value and a final value, makes use of a braking torque developed to match the torque developed by the door. The development is determined by parameters such as weight of the door, swivel arm of the centre of gravity of the door, swivelling angle and others, when the swivelling axis is at a maximum inclination with respect to the vertical. Since these parameters can differ widely from door to door, determination of the development of the torque of the door must precede the establishing of the development of the braking torque.
When a vehicle door is opened, if the vehicle is parked such that it tilts about the transverse axis, i.e. the vehicle is parked uphill or downhill, an advantageous braking torque of the swivel brake is therefore already provided if it, in this case, exceeds the torque of the door in all swivelling positions. It is thereby achieved that at least the potential energy of the door of a vehicle parked uphill is converted in particular into heat energy which does not pose a risk for the present case.
In order to also take into account a torque which occurs due to the vehicle being inclined about a longitudinal axis, a further object of the invention is for the braking torque to exceed the torque resulting from the inclination about the transverse axis by the torque resulting from the inclination about the longitudinal axis at the maximum opening angle of the door.
An advantageous balancing of the torques is achieved when the braking torque exceeds the torque resulting from the inclination about the longitudinal axis to a greater extent in the central region of the development of the braking torque than in the initial region and in the final region.
The initial braking torque when opening the door should not exceed a certain value in order to prevent the force required for this purpose from becoming too great. The torque of the door on the uphill side of a vehicle parked such that it tilts about its longitudinal axis is at the maximum in this region. However, since the distance available for building kinetic energy as the door is shutting is small, it nevertheless appears permissible to permit the braking force of the swivel brake to fall below the torque of the door in this region.
For the final value of the braking torque of the swivel brake at the maximum opening angle of a door, a moment has proven advantageous which corresponds to the sum of the torques acting on a door in the case of a vehicle parked such that it tilts to the maximum both about the transverse axis and about the longitudinal axis.
The invention has an objective of preventing, or at least of inhibiting, automatic, unintentional shutting of a car door which can result in injuries, in particular to passengers' legs. However, car doors which fall open automatically and unintentionally can also cause damage to vehicles parked beside them.
The opening of a door of a vehicle parked downhill, i.e. tilted forwards about the transverse axis, is in all cases prevented by the braking torque which exceeds the relevant opening torque. Opening of the door on the downhill side of a vehicle tilted about the longitudinal axis is not prevented, in the case represented and described by way of example, up to an opening angle of approximately 35.degree.. Up to this angle, the potential energy of the door is converted into kinetic energy, which is then absorbed, however, by the braking torque which substantially exceeds the opening torque.
According to the invention, the development of the braking torque can be realized on swivel brakes of differing design. Four differently designed swivel brakes on door hinges are represented and described by way of the following examples. However, development of the braking torque over the swivel path in accordance with the dimensioning rule according to the invention can also be imparted to swivel brakes which are separated from the hinge, for example in the form of brake loops.
Apart from in motor vehicles, doors having a varying inclination of their swivelling axis with respect to the vertical also occur, for example, in ships. The following description is directed primarily to car doors because the effect of the functionally correct dimensioning of a swivel brake can be shown particularly clearly on these car doors, whose operation is generally known.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawings.